The present invention relates to a method and apparatus for indicating the dynamic instability of railway or tramway rolling stock.
As is known, the dynamic instability which appears in railway and tramway rolling stock essentially consists in an oscillating phenomenon of the wheel arrangement of the rolling stock, which develops in a direction transversely of the direction of travel and which increases until it leads to the flange of the wheel rim knocking violently against the rail. In order to prevent the occurrence of this phenomenon from compromising the safety of running and/or from causing unwanted mechanical stresses to the wheel arrangement or to the railway track, it is sought to identify a critical velocity of the rolling stock itself and consequently to establish a maximum speed at which the rolling stock can travel.
It is however observed that the instability can also arise at speeds less than the critical speed or even very much less than the maximum allowed speed and this can occur, for example, because of a reduction in the lateral rigidity of the railway track, a gauge reduction, irregularity in alignment, wear of the wheel rims or else breakage and/or deterioration of the elastic and/or shock absorbing elements etc. In such conditions it is therefore possible that the instability phenomenon is triggered in an entirely unexpected manner, which, because of the filtering action exerted by the shock absorbing elements (for example the suspensions mounted between the carriage and the body, of the rolling stock), can even fail to be brought to the attention of the travellers in time, with consequences which can be extremely detrimental for the safety in movement of the rolling stock itself or even of the train of which the falling stock forms part.